title: Collapsing glomerulopathy superimposed on diabetic nephropathy: insights into etiology of an under-recognized, severe pattern of glomerular injury.
abstract: BACKGROUND
  Collapsing glomerulopathy (CG) represents severe podocyte injury with massive proteinuria, rapid progression and relative resistance to therapy. It is associated with multiple etiologies, including obliterative arteriopathy in transplants. However, its association with diabetic nephropathy (DN) has not been reported.
  
  
  METHODS
  Renal biopsies performed in diabetic patients for either increasing proteinuria or deteriorating renal function, or both, were retrospectively reviewed. The clinicopathologic features and immunohistochemical staining of podocytes were analyzed.
  
  
  RESULTS
  Of 534 patients with DN, 26 human immunodeficiency virus (HIV)-negative patients were found to have CG superimposed on DN (5% DN cases). At the time of biopsy, their mean serum creatinine was 3.8 mg/dL and proteinuria was 9.8 g/24 h. Renal biopsy showed CG in 2-30% (mean 16% of glomeruli), with segmental (2%) and global (33%) glomerulosclerosis. DN classification was Class IV-12, III-8, IIb-4 and IIa-2. Vascular sclerosis was moderate (44%) and severe (56%). Extensive arteriolar hyalinosis with >50% luminal stenosis was seen in 85% of cases. Markers of podocyte differentiation were lost, consistent with other types of CG. Cytokeratin was focally positive in 70% and VEGF overexpressed in 43%. Follow-up on 17 patients: 13 developed end-stage renal disease (ESRD) in 7 months from the time of biopsy. The development to ESRD in these patients was more rapid than diabetic controls without CG (P=0.005). The remaining four, 5-24 months follow-up, had an increase in creatinine with stable proteinuria.
  
  
  CONCLUSIONS
  CG contributes to an increased level or new onset of proteinuria in DN which may be intractable. CG in DN with advanced vascular hyalinosis is presumably due to ischemic podocyte injury and is of prognostic significance.
authors.affiliation: Department of Pathology and Laboratory Medicine, Weill Cornell Medical College, New York, NY, USA.
authors.forename: Steven P
authors.initials: SP
authors.lastname: Salvatore
authors.forename: Alluru S
authors.initials: AS
authors.lastname: Reddi
authors.forename: Chandra B
authors.initials: CB
authors.lastname: Chandran
authors.forename: James M
authors.initials: JM
authors.lastname: Chevalier
authors.forename: Chike N
authors.initials: CN
authors.lastname: Okechukwu
authors.forename: Surya V
authors.initials: SV
authors.lastname: Seshan
mesh_terms: D015415:Biomarkers / Q000097:blood; D001706:Biopsy; D003124:Colorimetry; D003404:Creatinine / Q000097:blood*; D003928:Diabetic Nephropathies / Q000097:blood / Q000150:complications* / Q000473:pathology; D018450:Disease Progression; D005260:Female; D005500:Follow-Up Studies; D005923:Glomerulosclerosis, Focal Segmental / Q000097:blood / Q000209:etiology* / Q000473:pathology; D006801:Humans; D007150:Immunohistochemistry; D007678:Kidney Glomerulus / Q000648:ultrastructure*; D008297:Male; D008854:Microscopy, Electron; D008875:Middle Aged; D050199:Podocytes / Q000648:ultrastructure; D011379:Prognosis; D012189:Retrospective Studies; D012720:Severity of Illness Index
chemical_list: D015415:Biomarkers; D003404:Creatinine
keywords: collapsing glomerulopathy; diabetic nephropathy; pathology; proteinuria